ClojureScript tip: mind the Clojure version

Updated the ClojureScript version, and now you're getting build errors? Check the Clojure version.

If you do an upgrade through lein ancient update, it will not upgrade the Clojure version. But if you have a ClojureScript dependency, it will be upgraded, and you may run into a case like this when building:

No such var: string/index-of, compiling:(cljs/source_map.clj:260:54)

I got this error when going from ClojureScript 1.8.34 to 1.9.93. I wasn't using index-of directly, which is a Clojure 1.8 function... but ClojureScript was.